647.    CROWELL, J. H., BENSON, H. E., FIELD, J. H., AND STORCH, H. H.  Fischer-Tropsch Pilot-Plant Studies of Oil-Circulation Processes at Bureau of Mines.  Am. Chem. Soc., 117^th Meeting Abs., March-April 1950, p. 5-J.

      Summary of Fischer-Tropsch process development is given in which the essential features of the German fixed-bed system, the hot-gas recycle and oil-circulation processes, and the oil-slurry and fluidized-bed system are briefly described.  Most of the pilot-plant experimentation at the Bureau of Mines has been directed toward the development of the oil-circulation process since a simple converter design could be used and precise operating control could be attained in such a system.  Several moderately successful experiments were performed that employed a cooling-oil circulation through a fixed catalyst bed. However, shutdowns were necessary after 3 or 4 months of synthesis because the catalyst particles became cemented together and an excessive pressure drop developed across the catalyst bed.  This problem of catalyst cementing was circumvented by employing a moving-bed catalyst in which the lifting action of the circulating oil was used to expand the catalyst bed and keep the particles in motion.  Details of induction and synthesis operations, operating data, analyses of gas and liquid streams, tables of calculated yields, and a typical product distribution are given for various experiments.  Calculations are made for a 2-stage process, with interstage scrubbing of CO₂, showing the C₁, C₂, and C₃ yields, which could be expected at 91% overall synthesis-gas conversion.